Diagnostic tests

Learn more about types of diagnostic tests used to understand causes of neurological symptoms and conditions.

Electroencephalogram (EEG) - An EEG test measures brain wave activity. It's helpful in the diagnosis of neurological disorders, from common headaches and dizziness to seizure disorders, strokes and degenerative brain disease. The EEG is also used to determine if there are physical causes of psychiatric symptoms as well as learning disabilities in children. An END technologist will apply small electrodes to the patient's scalp to obtain the electrical signals from the brain. The patient either sits in a recliner or lies on a padded cart. The test can take 60 minutes to complete.

Evoked Potential (EP) - The EP test is a recording of the electrical activity from the brain, spinal nerves or sensory receptors as they respond to external stimulation. There are three distinct types of EP tests, all performed while the patient is sitting in a recliner or lying on a padded cart.

The brain stem evoked response (BSER) test evaluates the auditory nerve pathways from the ears to the areas of the brain that evaluate sound. The test takes between 45 and 60 minutes.

The somatosensory evoked response (SSER) test assesses the pathways from the nerves in the arms or legs, through the spinal cord to the brain area responsible for interpreting body sensations. It can take approximately 60 minutes if only the arms or legs are tested, or at least two hours for testing on both arms and legs.

24 hour ambulatory EEG - The ambulatory EEG exam allows patients to experience a normal day's activity while a special device captures their brain wave activity. This test is often performed with patients who have a history of recurring seizures. A small tape recorder is worn and patients are asked to record activities in a journal.

Long-term EEG and video monitoring - Also known as video EEG monitoring (VEEG). When conventional EEG recordings are unable to collect enough information to treat patients with recurrent seizure-like episodes, the neurologist might suggest LTM. The patient is admitted to the hospital, wears special recording electrodes and stays in a room equipped with video cameras. This allows the physician to witness all seizure-like episodes and study the brain’s electrical activity at the time of the episodes.

Intraoperative monitoring - Both the EEG and SSER evoked potential tests are useful tools in the operating room. The EEG provides a "map" to areas of the brain such as speech, hearing and movement that may be emitting abnormal electrical discharges. SSER evoked response testing is helpful to assess nerve function during surgical procedures involving the spinal cord or brain.

Nerve conduction studies - This non-invasive procedure determines how quickly a specific nerve is able to transmit an impulse or message to the muscle. This exam helps the doctor determine where muscle weakness, pain or paralysis may exist in either nerve or muscle.

Electromyography – This diagnostic test is used to evaluate muscle function. EMG measures the electrical activity in nerves and muscles and helps detect the presence, location and extent of nerve and muscle disorders. Muscle weakness or paralysis may be a problem in the muscles, nerves in the muscle, the spinal cord or the area in the brain that controls the muscles. The test provides information about the cause.

Wada – This is an evaluation of the brain's language and memory function. The test is officially called the intracarotid sodium amobarbital procedure. The Wada tells which side of the brain has better memory and which side controls language. This test is most often performed when an epilepsy patient is considering surgery.